It's Monday morning, but the seven- and eight-year-olds of Bollington Cross primary in Cheshire are hopping from one bare foot to the other with excitement. They are in the changing rooms at their local leisure centre getting changed for their weekly swim. It takes 10 minutes to walk here; in an hour, they'll be back in class.

They don't know how lucky they are. Primaries are increasingly having to cut back on visits to pools and ask parents to help with the cost of transporting children to them, Education Guardian has found.

This is despite the fact that learning to swim is as compulsory a part of the national curriculum for key stage 2 - ages seven and eight - as maths is. Government guidelines state that by the time children complete primary school, they should be able to swim 25 metres. About 80% achieve this, the department for children, schools and families says.

"Schools cannot charge for providing swimming for their pupils, but they can ask for a voluntary contribution to the costs involved," says the DCFS spokeswoman. And this is what more and more schools are having to resort to, because pool closures mean the local baths can now be an expensive coach ride away.

Last month, figures from the British Market Research Bureau showed the proportion of teenagers who swim regularly had dropped dramatically in the past decade. One in four 11- to 18-year-olds swam weekly in 1993, now it's near to one in 10.

For primary children, swimming is meant to be free - but for many, in effect, it is not. Which rather makes a mockery of Gordon Brown's announcement last month of plans for free entry to swimming pools for over-60s, and for everyone by 2012.

Swimming cuts

Many heads are, reluctantly, deciding their pupils will have to go swimming less often. Aside from the cost, the time it now takes to get a class to the nearest pool can be twice as long as the lesson itself, as Ofsted found was the case for some schools in a report published in November.

School swimming pools are said to be disappearing at a rate of 10% a year in many areas and will have dropped to 750 nationally, from 3,000 in the 1980s. Sport England claims more pools have opened than closed in England since 2004. But new pools are often in leisure centres and have flumes and slides that aren't conducive to swimming lessons.

Several of the local authorities Education Guardian spoke to confirmed school pools in their area had closed in the last few years. Carol Lukins, of Suffolk schools' swimming service, says that in Suffolk the closures were brought about because school pools were small, outdoors and unheated, and new town pools had been built nearby.

The London borough of Hackney says many of its schools go out of the borough "due to catchment areas and available pool time". A spokeswoman says: "There have been approximately five pool closures in the past 10 years, mainly due to refurbishment and one permanent closure. Two new pools have opened, although one is unsuitable for children's lessons."

Rachael Winspeak, PE consultant for Buckinghamshire school improvement service, says: "There has been a decrease in school pools over the past 10 years due to the high cost of maintenance and upgrading pools. The majority of these pools were built in the 1970s."

Hertfordshire county council is just one local authority which admits its schools "ask parents for a contribution to the cost of swimming or transport to the pool".

Parents, it seems, are getting angry about having to pay the price for school pool closures. One mother from Surrey, who stumps up £35.50 for 10 lessons a term, says contributions for swimming are "voluntary" only in name: "I'd like to see any mother at our school dare say they weren't going to pay."

Another Surrey mother says: "Our school [a state primary] has never mentioned swimming. My son has private lessons costing £57 a term at a local independent school that has its own pool. What about families who can't afford to do this?"

In the chatroom of a government-endorsed website for parents, parentscentre, one mother says: "I received a letter from my son's school offering swimming lessons at the local leisure centre but asking for a voluntary contribution of £51 per child. There will be 11 lessons and the money has to be paid in advance.

"If the money collected does not cover the cost, then it will not be possible for the lessons to take place ... I have been trying to get the money together, but with three other kids, bills, rent, council tax etc, it is rather difficult."

A parent replies: "That is actually more than the posh leisure centre near me charges for kids' swimming lessons."

Costs of free provision

Professor Margaret Talbot, chief executive of the Association for Physical Education, says her organisation has also heard parents are increasingly being asked to pay for this "free provision".

"As part of the national curriculum, this should not happen," she says. "But it's easy to see why some hard-pressed headteachers ask parents for transport money."

Some, like Richard Redcliffe, are trying to find a solution that's cost-free. The headteacher at Ansdell primary in Lytham St Annes, Lancashire, has, over the past two years, persuaded a cluster of nearby primaries to appoint a swimming teacher and pay for transport and pool time together. But now the local baths are threatened with closure.

In Suffolk, Lukins says: "Over the last five to 10 years, there has been a steady decrease in the swimming undertaken in schools." But, she says, "swimming standards have not suffered. Generally, pupils swim for half a term at least once a week."

A spokesman at Liverpool city council says: "The vast majority of Liverpool schools provide swimming lessons, but a few cannot. Mainly, this is due to time and cost of transportation to and from the pool." Generally, primary pupils in Liverpool swim once a week, he says.

Winspeak says in Buckinghamshire "there are a small number of schools with key stage 2 pupils that do not provide swimming at all. The county is working with these schools to address the issues."

Rhiannon Jones, head of Kirkham and Wesham primary in Lancashire, says it's the children who don't excel academically, but gain a sense of achievement by developing sporting prowess, who miss out. If her local pool closes, as it is expected to in a year's time, pupils will have to travel for half an hour to Blackpool.

Nick Dowler, head of Nocton community primary in Lincolnshire, says if it wasn't for his local secondary school pool, his pupils wouldn't go swimming. "We couldn't get to a pool in a reasonable time - it's 13 miles into Lincoln. Our pupils have seven sessions over one term in years 3 to 6."

At David Tuck's school, Dallow primary in Luton, the pressure of Sats has made taking year 6 to the nearest pool and back unworkable. "I very much endorse the government's aspiration that every child should swim by the time they leave primary school, but sadly it's only an aspiration. For a child to learn to swim, they have to be able to get wet."

Talbot says one solution is to encourage pool managers to offer twice-daily swimming for a week. "This would halve transport costs and save time," she says.

In the meantime, it looks like swimming lessons are becoming a luxury rather than a national curriculum necessity. So much for combating the "obesity epidemic".

Learning potential

The Olympic swimming champion Duncan Goodhew, who campaigned for swimming to be kept on the curriculum in the 1980s and promotes the national Learn to Swim scheme, says children who don't get the chance to learn to swim are being deprived of a skill that saves lives and provides health benefits and fun. "The learning potential is colossal," he says. "Entering the water bombards the senses. Things look bleary, sounds are different and your body feels different. Children can't rely on the coping strategies they use on land."

Back at the leisure centre, the seven-and eight-year-olds of Bollington Cross are fishing about in the water for a metal hoop to hand back to their teacher. "I like going into the water," says Megan Muir, aged eight. "I didn't used to. I didn't like the feeling of water in my eyes. But I can do it now."

For Megan and her classmates, it's a short walk back to school for assembly at 10.15am. Unlike many of their peers, they'll be back next week, next term and next year.